Get Ready to Unleash the Power of UCanCode .NET

Danang Suharno
January 30, 2000
VC++ Source Codes
DocView architecture in MFC is not at all the fastest way to create a simple print preview. This article will explain How to create your own print preview. MFC DocView is designed to make the MSVC programmers get their works done in a minutes including print preview. Sometimes we need not to use DocView framework but we really need its print preview power. The key of this Print Preview is laying on the following function.

1. CreateCompatibleBitmap
2. CreateCompatibleDC
3. GetDeviceCaps
4. GetTextExtent

Beside those four functions, Print Preview needs a function that work for scaling and painting on the screen DC. We just lucky to have StretchBlt and BitBlt ready to do the dirty works but sometimes StretchBlt should be replaced by your favourite routine and then BitBlt comes into play. The reason is (maybe) dithering, filtering, anti aliasing etc..

void CDlgAneh::OnButton1()
{
// TODO: Add your control notification handler code here
//
//
// Design and implementation cinoban@yahoo.com
// 13 Jan 2000 15:14
//

CString strWords;

// This is a rectangle control
CWnd* pWnd = GetDlgItem(IDC_STATIC_PREVIEW);

CDC* dc;
CDC memoriDC;
CBitmap memBMP;
CBitmap* pOldBMP;
CFont fnt;
CFont* pOldFnt;
CRect rect;
CRect rectMemory;
CSize zMetrix;

//
//
//
CPrintDialog pdlg(FALSE);
DOCINFO di;
CDC prnDC;

di.cbSize = sizeof(DOCINFO);
di.lpszDocName = "This string will appear in Printer
Queue";
di.lpszOutput = NULL;
di.lpszDatatype = NULL;
di.fwType = 0;

//
// Get current printer setting
//
pdlg.GetDefaults();


//
dc = pWnd->GetDC();
pWnd->GetClientRect(&rect);

// DC printer???
if( !prnDC.Attach(pdlg.GetPrinterDC()) )
AfxMessageBox("Invalid Printer DC");
memoriDC.CreateCompatibleDC(&prnDC); // Create DC for
Preview

//
// Get the resolution of Screen and Current Default
Printer
//
int iPrnX = prnDC.GetDeviceCaps(HORZRES);
int iPrnY = prnDC.GetDeviceCaps(VERTRES);
int iMonX = dc->GetDeviceCaps(HORZRES); // Device
Target is Monitor
int iMonY = dc->GetDeviceCaps(VERTRES);


rectMemory.top = 0;
rectMemory.left = 0;
rectMemory.bottom = iPrnY;
rectMemory.right = iPrnX;

//
// Create a Memory Bitmap that is compatible with the
Printer DC
// then select or make the bitmap as current GDI
active object
//
memBMP.CreateCompatibleBitmap(&prnDC,
rectMemory.Width(), rectMemory.Height());
pOldBMP = memoriDC.SelectObject(&memBMP);

//
// Clear memory DC or in other words
// paint the bitmap with white colour and transparent
text
//
memoriDC.SetBkMode(TRANSPARENT);
memoriDC.SetTextColor(RGB(0, 0, 0));
memoriDC.PatBlt(0, 0, rectMemory.Width(),
rectMemory.Height(), WHITENESS);

//
// Prepare the font
//
int iPointz = 100;
fnt.CreatePointFont(iPointz, "OCR A", &memoriDC);
strWords.Format("This is line number    ");        //
Test string
pOldFnt = memoriDC.SelectObject(&fnt);
zMetrix = memoriDC.GetTextExtent(strWords);
int iPos = 0;

//
// Write string or Paint something
//
int iMaksimal = 0;
int iLineHeight = 1;
int iLoop;
CString strPuncak;

//
// Calculate how many lines we could fit
//
for(iLoop = 1; iLoop < 100; iLoop++)
{
if( ((zMetrix.cy+iLineHeight)*iLoop) < iPrnY )
iMaksimal++;
}

strPuncak.Format("Maximum Amount of line(s) for %d
points are %d lines", iPointz, iMaksimal);

//
//
//
for(iLoop = 0; iLoop < iMaksimal; iLoop++)
{
strWords.Format("This is line %d", iLoop);
memoriDC.TextOut(0, iLoop*(zMetrix.cy+iLineHeight),
strWords);
}

//
// Reseting font
//
memoriDC.SelectObject(pOldFnt);

//
// Calculate ratio
//
float fXRatio = (float) iMonX/iPrnX;
float fYRatio = (float) iMonY/iPrnY;


//  iLebar = Width
//  iTinggi = Height
//  iXPosisiPreview = horisontal location of preview
//  iYPosisiPreview = vertical location of preview
//
int iLebar = rect.Width()*fXRatio;
int iTinggi = rect.Height()*fYRatio;
int iXPosisiPreview = (rect.Width() - iLebar)/2;
int iYPosisiPreview = (rect.Height() - iTinggi)/2;
CPen pen(PS_SOLID, 2, RGB(255, 0, 0));
CPen* pOldPen;

//
// Create an outline
//
pOldPen = dc->SelectObject(&pen);
dc->Rectangle(iXPosisiPreview, iYPosisiPreview ,
iXPosisiPreview + iLebar + 2 , iYPosisiPreview +
iTinggi + 2);
dc->SelectObject(pOldPen);

//
// Put in the box
//
dc->StretchBlt(iXPosisiPreview , iYPosisiPreview ,
iLebar, iTinggi,
&memoriDC, 0, 0, rectMemory.Width(),
rectMemory.Height(), SRCCOPY);

//
// Cleaning Up
//
fnt.DeleteObject();
memoriDC.SelectObject(pOldBMP);
memoriDC.DeleteDC();
memBMP.DeleteObject();
prnDC.Detach();

//
pWnd->ReleaseDC(dc);
}